The 35th International Symposium on Halogenated Persistent Organic Pollutants (POPs), Dioxin 2015, will be held from 23rd to 28th August 2015, at the Hotel Maksoud Plaza, in So Paulo, Brazil. The past 3 decades have witnessed rapid advances in analytical and bioanalytical technologies for the detection identification, and quantitation of POPs, increased understanding of their formation, fate and transport, identification and characterization of new classes of POPs, and major progress in understanding their biochemical and toxicological mechanisms of action and adverse health effects. These insights, coupled with global distribution and the biological and environmental persistence of POPs, have made them a major issue of increased interest and concern of scientists and regulators, and a major challenge for some countries to reduce/minimize their presence in the environment, animals and food. Current research on these chemicals now encompasses a broad range of scientific disciplines, from analytical and environmental chemistry to molecular biology, toxicology and epidemiology. The broad and long term goals of this symposium are to bring together the world's experts in these diverse scientific areas of POPs research and to provide them with a unique multidisciplinary forum in which to communicate and discuss recent results and emerging issues, and to develop interdisciplinary collaborations and translational approaches to addressing the problems of global POP contamination. This meeting will provide such an opportunity for the 800-1000 participants expected for this four and a half day conference of more than 40 oral presentation sessions and three open poster sessions covering a diverse range of topics. Each day will commence with a plenary lecture by a leading international POPs expert followed by oral presentations in four concurrent sessions on a variety of POPs areas. The afternoon sessions begin with an open poster session attended by all participants, followed by two sequential blocks of four concurrent oral presentation sessions. The final day will conclude with an overall summary session describing significant advances reported during the meeting and discussing future challenges in POPs research. The national and international organizing committees will ensure that there will be significant participation by students, postdocs and young investigators, parity in the numbers presentations by women, minorities and persons with disabilities, and balance in the number of presentations by researchers from various regions of the world. The Dioxin symposium provides a unique opportunity for interdisciplinary communications and interactions among participants from diverse scientific backgrounds and disciplines but who have a common interest in POPs. These interactions and collaborations are expected to continue to result in major advancements and new insights into the formation, fate and distribution of these ubiquitous contaminants, their environmental impact and health effects.